Purpose :
There is growing evidence of the negative impact of self-luminous devices before bedtime on sleep. Recent studies report that their moderate levels of blue light are sufficient to induce strong melatonin suppression on young adults (Wood et al., 2013) (Chang et al., 2015). Only broadband orange tinted lenses have been used to limit this effect (Figueiro&Overington, 2015). We performed a cross-over randomized study in the home environment on young screen users to compare the effects of 3 narrow bandstop blue-blockers on melatonin production, sleep quality and visual comfort, compared to a clear lens and a dark-orange lens blocking all wavelengths up to 527 nm (‘dark’ control).

Methods :
19 healthy young adults (32.5 years ± 5.2 SD) participated in the study. Volunteers were evening screen users devoid of any major health problem. They were excluded for prescription medications (antidepressants, sleep medicine…) or major sleep disruption. Each eyewear was worn during 4 consecutive evenings per week, leading to a 5-week study. During these 4 nights, participants were asked to use screens starting 4 hours prior to their usual bedtime. Hourly saliva samples (Bühlmann) were collected and radioimmuno-assayed for melatonin concentration. Sleep staging was analyzed with a digital tri-axial accelerometer (MotionWatch). Visual comfort was also assessed. MANOVA with post-hoc Tukey tests were used for statistical analysis.

Results :
4-hour exposure to light from screens and low domestic lighting with a clear lens before bedtime significantly suppressed melatonin by 53 ± 7% (p<0.001) compared to the ‘dark’ condition. Two narrow blue-blockers significantly decreased this suppression below 25% (p<0.01). They also decreased sleep latency by 50% and improved sleep efficiency (p<0.05). Only one filter and the clear lens conveyed good visual comfort and aesthetics.

Conclusions :
This study brings a complementary proof for a home environment that low levels of blue light before bedtime are sufficient to induce a significant decrease in melatonin production and sleep quality, likely to lead to misalignment of circadian phase and chronic sleep deficiency. Interestingly, one narrow blue-blocker, providing higher visual comfort and better aesthetics than dark-orange tinted lenses, significantly impeded these effects.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.